The invention pertains to sonobuoys for detecting underwater craft and other vibration producing means by the use of vibration sensing transducers, and particularly pertains to the deployment of sonobuoy components from a casing, and structure for releasing the components therefrom.
Sonobuoy devices are widely employed for submarine detection purposes, and are also utilized for underwater geological exploration and other submarine purposes. Sonobuoys may be either active, wherein a transmitted signal is produced, and the reflected signal is received and transmitted, or the sonobuoy may be passive wherein received signals are sensed and transmitted.
Sonobuoy devices are normally located as desired by aircraft, or watercraft. When airdropped, sonobuoys normally employ velocity reducing devices such as fins, foils or parachutes in order to retard the velocity of the sonobuoy casing as it falls through the air, and minimize the likelihood of damage as it enters the water. Also, such velocity control devices orient the sonobuoy as it falls through the air such that a predetermined end thereof will initially enter the water.
Upon the sonobuoy entering the water the components thereof, such as the sound producing and/or receiving transducers, transmitters, damping means, and other conventional components are deployed from the casing in order that they might best perform their desired function. With some sonobuoy constructions the sonobuoy casing itself floats upon the water surface and the components are dropped therefrom. This type of device is shown in U.S. Pat. Nos. 3,093,808 and 3,646,505. Other constructions utilize a float which is ejected from the casing, and the components are dropped from the casing to a considerable depth below the float.
With advancing technology permitting submarines to effectively operate at incresingly greater depths, the need for detection sonobuoys operating at increased depths arises, and present specifications often require that the sonobuoy transducer be located in excess of 100 feet below the water surface. It will be appreciated that in sonobuoys wherein the transducer and other components are ejected from the lower end of the casing to freely fall through the water, considerable time lapse occurs before the transducer reaches such operating depths due to the resistance of movement of the components through the water. As the components normally include lengthy wires and coils, including irregularly shaped housings and the like, considerable resistance is produced as the components fall through the water, and the time lapse from water entry until the transmitting of signals at the desired depth may be such that the submarine endeavoring to be located moves beyond effective locating range.
In view of the need for a sonobuoy capable of quickly becoming operative at the desired depth after entry into the water, considerable effort has been expended endeavoring to overcome the inherent problems.
Additionally, in view of the forces imposed upon the airdropped casing on impact with the water, it is important that positive and dependable release means be associated with the sonobuoy parachute or velocity restraining apparatus to prevent entanglement of the sonobuoy components therewith during deployment. Additionally, release of the sonobuoy components from the casing must be in a positive manner not likely to be adversely affected by the drop conditions. Previously employed release mechanisms have been unduly sensitive, subject to premature release, or prone to bind and not fully release, and were also prone to damage during the drop, resulting in an inoperative sonobuoy.